1. Field of the Invention
The present invention relates to an encoding device for moving images which encodes moving image signals by means of digital processing, and particularly to a variable frame rate type moving image encoding apparatus which appropriately controls the frame rate in accordance with the amount of image data to be produced and encoded.
2. Prior Art
In cases in which signals of moving images are transmitted, it is necessary to reduce the amount of data which is transmitted as much as possible by means of encoding. This is termed band compression, and in this type of moving image encoding apparatus, the encoded amount which is produced varies depending on the violence of the motion of the subject images, so that a method is known in which in accordance with the encoded amount produced, appropriate control of the frame rate (frame dropping) and control of the quantization step size of the image signals are conducted, and the time resolution and space resolution are controlled. For example, in Japanese Patent Application, First Publication, Laid Open No. SHO 63-102482, a method was disclosed in which control of the frame rate was conducted by means of an accumulated amount in a transmission buffer memory.
In the above described prior art, the frame rate alone was controlled in accordance with the accumulated amount of the transmission buffer memory, independently of the control of the quantization step size, and ideal control of the time and space resolution could not be conducted, so that there was a problem in that improvement in picture quality was limited.